Ion trap



Patented Feb. 26,1195! zen 924 UNITE STATES PATENT, OFFICE 2,542,924 1 t Myron B. lie pg zei zi und L ake, Ill.

Application June 21,133 3 1:0. 189,418

1 8 Claims.

This invention relates to improvements in an ion trap for cathode ray tubes and refers particularly to an improved economically constructed, conveniently attached ion tray construction.

In the operation of the usual cathode ray tube the discharge of electrons in the form of a stream within the tube is accompanied by ionization of residual and occluded gases within'the tube. Bombardment by the ionsso formed upon the fluorescent screen of the tube very quickly destroys the fluorescent screen.

It is known-that electrons are responsive to a magnetic field and a stream of electrons may be diverted when acted upon by a magnetic field. The same holds true for ions except that the degreeof diversion of a streamof electrons and a stream of ions when acted upon by a predetermined magnetic field is different. the electron stream being diverted to a greaterextent than the ion stream.

Advantage is taken of this phenomena in the use of a cathode ray tube by disposing in the electron stream so that it moves through the nomical in construction and which is eiiicient present invention will be apparent from the accompanying drawing and following detailed description.

In the drawing,

Fig. 1 isa side view of a conventional cathode ray tube, parts being broken away and parts being shown in section, illustrating 'my ion trap mounted upon the neck of the tube.

Fig 2 is a fragmentary detailed top plan view a portion of the neck of the tube.

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 1.

Fig. 4 is an enlarged sectional view taken through one of my improved units.

Fig. 5 is a detailed perspective view of the magnet retainer clamp.

opening in a more or less axial fashion with respect to the tube. The accompanying ion stream, however, being acted upon by the same field, but not being diverted to the extent of the diversion of the electron stream, strikes the barrier, that is, the electron stream is caused to miss the opening. In effect, therefore, the ions are filtered" from the electrons and cannot exert their destructive effect upon the fluorescent screen.

The present invention relates particularly to a magnetic field-producing device, commonly re- I ferred to as an ion trap. :which may be conveniently mounted upon the neck of a cathode ray tube to divert ,or bend the electron stream and the ion stream to axially orient the former and causethe latter to be obstructed.

Fig. 6 is a fragmenary perspective view of a portion of the magnet retainer.

Referring in detail to the drawing. I indicates generally a conventional cathode ray tube having a restricted neck 2 and a flared forward portion 3. A face 4 is carried at the fiared end of the tube, the inner surface of the face carrying a fluorescent screen 5. At the opposite end of the tube, a base 6 is carried having contact prongs I for making contact with appropriate circuit elements for the tube.

Other elements are normally "associated with the tube, such as the horizontal and vertical controls, focusing and centering devices and the like. However, for purposes of clarity these elements are not shown, since, in themselves they are not inter-functionally related to the present invention.

The tube I carries interiorly thereof adjacent the base 6 a so-called electron gun 8 whose function is to discharge a stream of electrons designated by the dot-and-dash line. Intermediate the neck 2, a barrier 9 is carried having a substantially centrally positioned aperture It. In this form of tube, the gun 8 is so arranged as to initially direct the electron stream at an angle to the axis of the tube, as indicated at H in Fig.

As a feature of the present invention an ion- 1 trap is, contemplated which is simple incon-- struction, its workable elements or poles, whose] primary function is to selectively orient the electron stream, functioning additionally to mountthe device on the tube neck.

ll further feature of the invention resides in a construction which is light in weight; is eco- '1. .Eventually, the stream of electrons is projected through aperture l0 substantially along the axis 01' the tube, as indicated at I! in Fig. 1, after the stream has been bent and oriented as will be hereinafter more fully described. 1

The device contemplated in the present invention comprises a unit assembly II including arms I and [5, a magnet retaining portion It, a mag-' net retaining clamp II anda magnet It. The

22 and web 2|. portion I6 and the clamp I1 is moved along the arms I4 and I5 andthe magnet retaining portion I5 are formed from a strip of ferro-magnetic material such as steel and are possessedof sufficient resiliency to engage the neck 2 of the tube I, as shown best in Fig. 3, the arms being arcuately curved and the ends IQ of thearms being spaced from each other and being outwardly turned. Intermediate arms I4 and I 5, the strip is bent to form a substantially channel section, as shown best in Fig. 6 to embrace the rectangular sectioned permanent magnet I5.

To secure the magnet I8 firmly in contact with the walls of the magnet retaining portion I8 so that a path of minimum reluctance is offered to the flux between the surfaces of the magnet and the surfaces of. the portion I 6, the clamp I1 is employed.

The clamp I1 is substantially channel shaped, having side flanges and a central web portion 2I. At the ends of the flanges 20 inturned tongues 22 are formed. The clamp IIis constructed of a non-magnetic metal such as brass, bronze or the like and is of suflicient thickness to rigidly clamp'the magnet I8 and retaining portion IBin intimate contact with each.other.

In assembling the device I3 a straight strip of ferro-magnetlc material, such as steel, is bent intermediate its length to form the channelshaped magnet-retaining portion IS.. The arms I4 and I5, at this stage are not curved, but com- I prise straight continuations of the flanges of the channel-shaped portion IS, the arms being disposed parallel to each other. The member I1 is then threaded upon the ends of the arms, the arms being respectively positioned in slots 23 at each end of the device I! between the tongues Magnet lfi is positioned in the then straight arms I4 and I5 until the web 2| abuts the lower face (Fig. 4) of the magnet. The arms-I4 and [Sam then arcuately shaped, as shown, and the webs 20 of the clamp H are squeezed inwardly into snug contact with the side edges of the magnet and tongues 22 are moved downwardly (Fig. 4) into contact with the respective 'arms' I4 and I5. The clamping member Il thus securely wraps the magnet-retaining portion I6 into snug contact with the magnet and holds, these elements in relatively efiicient magnetic contact with each other.

As has been hereinbeifore described, arms I4 and I5 embrace the neck 2 of the tube land are possessed of the requisite resiliency to hold the device [3 relatively immovable upon the tube. In order to facilitate the gripping action of the arms, elastic sleeves 24 and 25 may embrace the arms I4 and I5, respectively, adjacent the portion I5. For convenience, the sleeve 24 may be of a different color than the sleeve 25. For example,

I I4 and I5 and the channel portion I6, prior to being bent and assembled as hereinbefore described, is provided with an aperture 26 which is preferably positioned at the central portion of the strip. It will be noted that the provision of the aperture 25 forms relatively restricted connecting portions 21 (Fig. 2) whichform a magnetic path between opposite ends of the magnet II. The

restricted dimensions of the connecting members 21 are such that they are saturated by the mailnet II and hence a difference of magnetic potential is established between the arms I4 and II. As will be hereinafter more fully described, it is this diil'erence in magnetic potential which establishes the magnetic field through which the electron and ion streams are passed and which orients the electron stream axially so that it passes through the'central aperture I. in the barrier I while simultaneously causing the ion stream to impinge upon the barrier.

In employing my invention the unit II is positioned upon the neck 2 of the cathode ray tube I and is so disposed lengthwise along the neck 2 that the electron stream II will be so diverted or bent as to pass through the aperture II. Of

, course, the strengthof the magnet II taken in Ill) gate the ion and electron streams, it is to be understood that two or more such units may be employed if desired depending upon the direction of discharge of theelectron stream from the electron gun and the angle which the initially discharged stream makes with the axial center of the tube.

I claim as my invention:'

1. A permanent magnet structure for use as an ion trap for a cathode ray tube comprising a onepiece ferro-magnetic strip, a permanent magnet having a north and south pole embraced by and in magneticcontact with an intermediate portion of said strip, non-magnetic means for clamping said intermediate portion in snug contact with the north and south poles of said magnet, said strip terminating in oppositely extending spaced arms for embracing the neck of a cathode ray tube, an intermediate portion of said strip adjacent its contact with said magnet and be tween said north and south poles of being of relatively restricted sectional dimensions and being magnetically saturated by the magnet embraced.

2. A permanent magnet structure for use as an ion trap for a cathode ray tube comprising a relatively elongated, relativel thin one-piece strip of resilient ferro-magnetic material, a channel formed intermediate the length of said strip, a permanent magnet positioned in said channel, a non-magnetic clamp for holding said strip in snug magnetic contact with said magnet at its ends and a side thereof, said channel being provided with an aperture to form of said channel magnetic paths of restricted cross section between the ends of said magnet, restricted crosssectional portions of said channel being saturated by said magnet, said strip terminating in spaced arcuate arms for resiliently embracing the neck of a,cathode ray tube to establish a magnetic field across said neck between said spaced arms.

3. A permanent magnet structure for use as an ion trap for a cathode ray tube comprising a relaa of said strip, a permanent magnet of rectangular section positioned in said channel, a non-magnetlc cla'mp for holding said strip in snug magnetic contact with said magnet at its ends and a 2,542,924 6 side thereof that portion of the channel in con- REFERENCES CITED tact with the side of the magnet being provided The following references are of record in the with an aperture to form of said channel ma me f thi patent netic paths of restricted cross-section between the ends of said magnet, said restricted cross- TED STATES PATENTS sectional portions of said channel being mag- Number Name Date netically saturated by said magnet, s id strip ,6 B w Aug. 13, 1940 terminating in spaced arcuate arms f r l- ,4 ,625 White June 21, 1949 iently embracing the neck of a cathode ray tube 2,49 ,1 7 Kelar Jan. 31, 1950 to establish a magnetic field across said neck be- 10 39 54 m m F b, 21, 1950 tween said spaced arms. 2,499,065 Heppner Feb. 28, 1950 MYRON R. HEPPNER. 2,500,455 Fisher Mar. 14, 1950 

